If you're passing it in just for this one time, and you don't need to maintain the parameters you can give your main function, you can convert the char* parameters the C++ runtime provides your program with by using int i = atoi( argv[1] ).

If you're going to have more parameters, you probably want some way to name them, too. Then it's worth taking a look at the getopt function. This one allows for more flexible command line parameters.

There even are command-line parsing frameworks out there that allow for type-checking and the lot.